With the growth of the Office in the late seventeenth century, clearer distinction was made between the functions of its military and civil officers. Responsibilities and developments in specialist roles, for example, in military engineering and civilian draughtsmanship, became more acute as cartography emerged as a particular tool of government. In the Rules Orders and Instructions issued in 1683, the duties of State engineers and their role in map making is clearly defined for the first time. The Principal Engineer was to take ‘Surveys of Land … to draw and design the Situation of any Place in their due Prospects, Uprights and Perspective’. His knowledge of civil and military architecture was to give rise to ‘perfect Draughts of every Fortifications, Forts and Fortresses of Our Kingdoms … and to know the Importance of every one of them, where their Strength or Weakness lyes’. And, in times of action, he was to conduct sieging operations (Frederick 1683-1760: 52, 54, 55). Although the Rules were amended in 1686, the duties of the engineers remained largely unaltered and, thereafter, were approved by every sovereign of Britain from William III to George II. As part of the development of the civil branch of the Ordnance, a Drawing Room was established at the Tower of London, possibly as early as 1683. Crucial in its ensuing evolution was the instruction in the Rules to ‘cause the Draughts or Designs thereof to be left in the Office of Our Ordnance, there to remain for the Use and Information of Our said Master General and Principal Officers of Our Ordnance as Occasion shall require’ (Frederick 1683-1760: 53). In January 1694, the Ordnance engaged its first permanent draughtsman. Lucas Boitout was charged with the sole task of ‘Making, Draughting, and preparing such Plans, or Draughts … as shall bee Required and Directed By the Master General … or Principal Officers’ (quoted in Parnell 1995: 93). From this time onwards, the Drawing Room became a centre of carto-reproduction. Apprentices from the age of 12 were trained as draughtsmen and surveyors to complement the engineers in the field and to help with the compilation, drawing, correction, reduction, enlargement and copying of maps and plans (Harley 1978b).